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Can one of you truckers explain what an engine brake is?


jsharr

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I just heard a truck go past our building and you could hear him engine braking.  I do not know how this works.  I assume you somehow use engine compression to downshift and slow down the truck.

I know I can google it, and I probably will, but I would like real world explanations of what it is and when it is used.

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37 minutes ago, Longjohn said:

How cum nobody is posting?

I was blocked from posting, then looked at the The Café main page and saw the latest comments on all threads but one were a couple hours old.

So I went to Costco, got a 4.5 lb rotisserie chicken for $4.99, then ended up spending $123 total on stuff I couldn't pass up like 2 lb of garlic butter shrimp for $11.99 ($4 instant coupon).

A leg quarter with some nuked potatoes and half a can of French Style Green Beans and I had a filling dinner for $4.99/6 plus about another buck so a $1 delicious meal.  I also found chocolate lovers Twinkies in Walmart, so 35 cents for dessert plus $17.96/24 for the Diet Snapple I drank, so about $2 for the whole supper.

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4 hours ago, jsharr said:

I just heard a truck go past our building and you could hear him engine braking.  I do not know how this works.  I assume you somehow use engine compression to downshift and slow down the truck.

I know I can google it, and I probably will, but I would like real world explanations of what it is and when it is used.

its very loud. I was camping next to the Mackinac Bridge:blink:

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20 minutes ago, bikeman564™ said:

its very loud. I was camping next to the Mackinac Bridge:blink:

You get used to the constant noise.  Hard to believe but you do.  I lived at the intersection of 2 interstate highways in downtown Milwaukee for 2 years at college, on the 16th floor of this dorm, my room faced south towards the intersection.  The red X below.    Even when the windows were closed in the winter I heard jake braking all night long, the trucks slowing down for all of the ramps.  

I'd go home for holidays, etc.., and to was tooooo quite and that's when I could not sleep. 

image.thumb.png.d3ade32038ed4acf408702b475f30ddb.png

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The short version is that the exhaust valves are mistimed to open at the top of the compression stroke effectively causing the engine to act as an energy absorbing air compressor.

The long story is how it is accomplished.

Originally designed to work on engines with cam actuated injectors, a master piston actuated by the injector push rod hydraulically actuates the exhaust valves on the same cylinder when the solenoid valve closes the oil gallery between them.

On engines with Bosch type injection, it is a bit more complicated

 

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When Pratt and Whitney laid me off back in 92, one of the first companies I applied for work at was Jake Brake. The job posting was for test cell technician and because I had worked in Pratt's test cells I thought it would be a good fit.  They thought I was overqualified.

Years later I ended up directly across the street from them at the laser company.

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11 hours ago, BR46 said:

Engine brake is when you are leading the race and you hear a little ticking noise. When you pull off the race track and you find this inside your motor. 

This is Engine braking 

20240211_170314.thumb.jpg.97cd74403eb6e9b847041c7bf3438fce.jpg20240211_170247.thumb.jpg.a3a5e3d37e35c57849bb52ff8b1a03b0.jpg20240211_170230.thumb.jpg.6ca9a2a1fd10eb18ff5b041c29afe3dd.jpg

They always run best just before they blow!

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2 minutes ago, groupw said:

They always run best just before they blow!

They are getting hotter and making more energy.

A normal top fuel pass approaches white hot on the valves in the engine.  One small step for mankind later the heads of the valves melt and pop off allowing the flame front to move up into the supercharger.

HUGE Fire for Top Fuel pilot McMillen at the #SpringNats in Houston -  YouTube

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11 hours ago, BR46 said:

Engine brake is when you are leading the race and you hear a little ticking noise. When you pull off the race track and you find this inside your motor. 

This is Engine braking 

20240211_170314.thumb.jpg.97cd74403eb6e9b847041c7bf3438fce.jpg20240211_170247.thumb.jpg.a3a5e3d37e35c57849bb52ff8b1a03b0.jpg20240211_170230.thumb.jpg.6ca9a2a1fd10eb18ff5b041c29afe3dd.jpg

Your rod has Peyronies Disease! 

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56 minutes ago, maddmaxx said:

When Pratt and Whitney laid me off back in 92, one of the first companies I applied for work at was Jake Brake. The job posting was for test cell technician and because I had worked in Pratt's test cells I thought it would be a good fit.  They thought I was overqualified.

Years later I ended up directly across the street from them at the laser company.

Dr Evil Laser GIF

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In many locations in the Mitten (at least the Great West Mitten) using your Jake Brake is outlawed.  I see signs at township and city lines explaining this and simple "No Jake Breaks" signs at the top of hills.  I was led to believe that, in addition to the loud noise, it can cause excessive wear on the asphalt surface.  

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1 hour ago, maddmaxx said:

When Pratt and Whitney laid me off back in 92, one of the first companies I applied for work at was Jake Brake. The job posting was for test cell technician and because I had worked in Pratt's test cells I thought it would be a good fit.  They thought I was overqualified.

Years later I ended up directly across the street from them at the laser company.

That would have been before they spun off the vehicle systems as a separate company. In 82, I was field testing a new model brake and had occasion to call Jacobs a few times. When they answered the customer service line they would ask chucks or brakes.

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57 minutes ago, Kzoo said:

In many locations in the Mitten (at least the Great West Mitten) using your Jake Brake is outlawed.  I see signs at township and city lines explaining this and simple "No Jake Breaks" signs at the top of hills.  I was led to believe that, in addition to the loud noise, it can cause excessive wear on the asphalt surface.  

Don’t know where you heard that but it is nonsense. Retarding power doesn’t exceed pulling power by that much. 

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18 hours ago, MickinMD said:

I was blocked from posting, then looked at the The Café main page and saw the latest comments on all threads but one were a couple hours old.

So I went to Costco, got a 4.5 lb rotisserie chicken for $4.99, then ended up spending $123 total on stuff I couldn't pass up like 2 lb of garlic butter shrimp for $11.99 ($4 instant coupon).

A leg quarter with some nuked potatoes and half a can of French Style Green Beans and I had a filling dinner for $4.99/6 plus about another buck so a $1 delicious meal.  I also found chocolate lovers Twinkies in Walmart, so 35 cents for dessert plus $17.96/24 for the Diet Snapple I drank, so about $2 for the whole supper.

This has to be one of the Mickest posts of all Mick's posts!!!

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17 hours ago, Rattlecan said:

The short version is that the exhaust valves are mistimed to open at the top of the compression stroke effectively causing the engine to act as an energy absorbing air compressor.

The long story is how it is accomplished.

Originally designed to work on engines with cam actuated injectors, a master piston actuated by the injector push rod hydraulically actuates the exhaust valves on the same cylinder when the solenoid valve closes the oil gallery between them.

On engines with Bosch type injection, it is a bit more complicated

Excellent explanation.

I may be thinking wrong, but doesn't that effectively make it  a massive vacuum cleaner?

Engine braking is different.  It's just taking your foot off the gas and letting the now basically idling engine to slow you down.

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17 hours ago, Rattlecan said:

The short version is that the exhaust valves are mistimed to open at the top of the compression stroke effectively causing the engine to act as an energy absorbing air compressor.

The long story is how it is accomplished.

Originally designed to work on engines with cam actuated injectors, a master piston actuated by the injector push rod hydraulically actuates the exhaust valves on the same cylinder when the solenoid valve closes the oil gallery between them.

On engines with Bosch type injection, it is a bit more complicated

You had me at short version....

You lost me at long version

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3 hours ago, Rattlecan said:

Don’t know where you heard that but it is nonsense. Retarding power doesn’t exceed pulling power by that much. 

I didn't say I knew what I was talking about.  I said I was led to believe.

Now let's talk about how that slightly exceeding retarding power is applied.  Not evenly like 'pulling power' is.  It's applied in an earth-rattling inconsistent hammering of the drivetrain.  Could that do damage to hot soft asphalt on an August afternoon?  You tell me.

I live at the intersection of 2 roads at the bottom of a pretty deep valley.  All 4 roads go up from my corner.  One of those roads is the busiest north-south road in the county (not considering the interstate several miles to the west).  We get a bunch of semi-traffic north-south and some east-west (mostly construction and ag).  No Jake Breaking near me. 

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6 hours ago, Kzoo said:

In many locations in the Mitten (at least the Great West Mitten) using your Jake Brake is outlawed.  I see signs at township and city lines explaining this and simple "No Jake Breaks" signs at the top of hills.  I was led to believe that, in addition to the loud noise,

I'm sure it's just about the noise.  

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2 hours ago, Kzoo said:

I didn't say I knew what I was talking about.  I said I was led to believe.

Now let's talk about how that slightly exceeding retarding power is applied.  Not evenly like 'pulling power' is.  It's applied in an earth-rattling inconsistent hammering of the drivetrain.  Could that do damage to hot soft asphalt on an August afternoon?  You tell me.

If that was true, it would impact the tires and drive train more than the road.

If that was a concern, you can bet cost contious fleets would deactivate them. 

Heavy engines pretty much come with the engine brakes integrated nowadays.

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3 hours ago, Longjohn said:

It’s been proven that a Jake Brake makes less noise than a tractor trailer crashing into your house.

Trucks used to regularly wind up in the river by getting oot of control on the big hill near my childhood home. They put in one of those gravel runaway truck ramps and the carnage seems to have stopped. Weird I can’t remember hearing Jake brakes. And I don’t remember seeing a no Jake brake sign either. 

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